Case Studies
ADCO
Abu Dhabi Company for Onshore Oil Operations (ADCO) approached Wireless Measurement to tackle the problem of monitoring production on a sample of six oil wells located in the Arabian Desert.
The wells were selected close to the edge of the field in the vicinity of water injection wells, used to maintain reservoir pressure. On occasions water break-through had given rise to the need for costly maintenance procedures resulting from inefficient production and increased corrosion. The selected wells are free-flowing and are located in soft desert sand. There is no electrical power supply on site or close by so the solution needed to be self-powered. The soft sand, combined with the need to carry out regular (3-5 year) work-overs, rendered impractical laying any cables from the wellhead to an instrument cabinet.
The installation of wireless pressure and temperature sensors on the wells, combined with real time data transmission to a web based server now enables the operator to view the well performance in real-time. Warnings and errors are flagged up so that an appropriate and immediate response can be made. On one of the wells a solar powered Cathodic Protection system is also connected enabling hourly performance reports in place of the monthly reports previously only obtained by a field visit.
The installation for ADCO made use of the existing GSM network which
covers the desert field using an open GPRS connection to the server for
continuous real time feed of measurements. The network was also used for
distribution of SMS messages to field workers. The system comprised a
number of wireless combined pressure and temperature sensors, GPRS based
WellSite Controllers (with a solar power suply with backup for night
time operation) and the Server based Server hosted on ADCO’s own
IT infrastructure. In addition a programmable low power radio interface
was added to an existing Cathodic Protection system to demonstrate the
capability of the system to interface to proprietary, as well as
standards based, third party equipment.
The system has been in
continuous operation in the field since April 2009. During this time
there has been no field equipment failure and, on only a handful of
occasions, has field equipment needed to be reset for any reason. After
11 months’ operation, one sample sensor was temporarily removed for
inspection and to check its calibration against a pressure reference.
The sensor was found to be measuring within 0.5% as per original
specification with no adjustment necessary. The server software has been
upgraded with user interface changes requested by the client and has
had some periods of down time due to hardware
and IT hosting issues.
In any large scale deployment the software would be installed on
multiple servers with redundancy and automatic failover.
These periods of downtime have served to demonstrate the
effectiveness of the automatic data retrieval from the inbuilt data
logging capability of the sensors. Overall system was measured after the
first six months’ operation. Since each sensor was reporting a pair of
measurements every 2 minutes, a total of 7.8M readings could have been
recorded in the database. Of this total potential data, the system had
captured 98.7%.
The potential savings associated with deploying
this technology more widely have been analysed as follows: The present
practice of monitoring wells by visual inspection every 2-3 days means
that any shut-in caused by over/under pressure or accidental trip may go
undetected for up to 3 days. The cost in deferred production averages
at about 1½ days, or 3-4,000 bbl per incident.Since unplanned shut-in
events take place on average at least twice per year, this equates to a
1% effective capacity increase. In today’s market these losses are
accommodated in the margin between agreed production quotas and overall
production capacity. Remote monitoring of three critical
parameters – hydraulic control pressure, annulus pressure and chemical
injection tank levels – would reduce total field visits by one third.
Not only is this a major cost saving, but it also represents a major
improvement in exposure of personnel to health and safety hazards
associated with desert travel and field visits.
The Cathodic Protection units are visited every two months for data
to be downloaded using a laptop for analysis back in the field office.
The control panels are frequently inaccessible due to sand build up
blocking the enclosure door. When this happens, another team is called
to clear the sand before a third site visit can be carried out to
finally access the data. Once retrieved, the data is analysed. Any
problem or failure of the system may be up to 60 days earlier resulting
in unnecessary corrosion of the protected asset.
In evaluating
Wireless Measurement’s remote monitoring capability in the hostile
environment of the Arabian Desert, ADCO have concluded that the system
is both robust, reliable and that the instruments maintain excellent
accuracy. The remote monitoring capability reduces the number of
necessary field visits which carries both a substantial financial saving
and reductionin exposure of workforce to risk. A substantial increase
in Effective Production Capacity yields potential increased in revenue.
The ability to respond to events in real time reduces risk to assets and
enables losses or equipment damage to be minimised.